This is my third book by Robert Silverberg but my first disappointment. Not up to the high standard I was led to expect by the other two.
Amidst one man's obsession with making first contact with aliens, no matter what the expense, is a struggle by sentient androids for equality with humanity. For the "vat-born" to stand along side the "womb-born". But to their creator, who they see as their god, sees them only as things; as a means to achieving his ends.
Unconvincing character developments and motivations undermined my enjoyment of this book though. No light whatsoever was shed upon the strange but persistant alien communication there were receiving. I feel that this could have been handled a bit better.
Coincidentally, unlike the other two I read, this featured hard science quite heavilly. Perhaps he's best leaving such things in the more capable hands of others and concentrating on those things he does best?